1. Field of the Invention
The present invention relates to an imaging apparatus such as a copier or printer, equipped with a document circulating feeder, which has a construction for restoration control at the document-circulating feeder end in the event of trouble occurring at the imaging apparatus end, as well as to a sheet-circulating feeder for feeding document sheets to a processing station such as a copyboard or the like.
2. Description of the Related Art
When making multiple copies from a number of documents, imaging apparatuses, for example copiers for copying images of documents, automatically feed the documents to a copying station, i.e. a light exposure station, and produce the desired number of copies. During the process, the outputted copied sheets are sorted by a sorter equipped with a plurality of trays, as means for placing the copied sheets in the serial page order of the documents.
With the aim of eliminating the need for such sorters, there have been proposed and put into practical use, as document feeders for the above-mentioned type of apparatuses, automatic recirculating document handlers of the type which produce only one copy each time the document to be copied is passed through the light exposure station, without producing all the indicated number of copies once, and then return it back to the document tray for its recirculation once again to the light exposure station. In this manner, since the circulating documents are copied one page at a time, the copied sheets are outputted after being collated in the same serial page order as the documents, and thus the circulation of the documents also serves as a sorting operation, eliminating the need for a sorter and allowing the device to be made smaller.
As a conventional measure against cases where trouble occurs while feeding the documents, such as jams at the automatic recirculating document handler (RDH) end or the copying unit end, there is provided means at the RDH end for jam recovery, i.e. for resuming copying, after the jam has been cleared, from the document at which the jam has occurred. For example, in the case of an automatic recirculating document handler such as the one disclosed in Japanese Patent Publication JP-A 1-166056 (1989), a job resuming function returns documents which have jammed at the RDH end back to the RDH in the correct order. There is disclosed a resuming function in which, when jamming of a document occurs at the RDH, the location of the fed but suspended document is determined and a paper feeding path separate from the circulative feeding path is used for restoration to resume copying in the order of the documents.
Furthermore, when the jam is not at the RDH end but at the copying unit end, the process is halted at the RDH end in the state at which the jam occurred, until the restarting of the copywork from that point after the jammed paper is removed. That is, since the jam is not at the RDH end and thus the feeding of the document has been properly performed, and the document is suspended at that position, the copying process may be resumed from the state prior to the jam after the jam has been cleared, thus completely solving the problem.
However, in cases where the feeding of the documents is halted at the RDH end due to a jam at the copying unit end or trouble other than a jam, if the document is suspended in a path in which it is inverted, curling, etc. of the document will occur and cause further jamming by the same document when the process is resumed. Particularly when circulative feeding is employed, the documents on the document tray are circulatively fed the number of times corresponding to the number of copies to be made, and thus the possibility of jamming becomes quite high. This possibility is even higher in the case of duplex copying, in which each duplex copy is made only after recirculation.
Here, it may be a solution to the trouble to feed the document, without allowing it to lie there until the solution of the trouble occurring at the copying unit end, through the RDH end (without exposing the document to light) and returned to the document tray in the original state for copying. That is, since the trouble has not occurred at the RDH end, there is absolutely no problem with the feeding of the document, and thus the document may be circulatively fed as if copying were being made normally, and returned to its original loaded state on the document tray. Then, after the trouble has been solved, normal copying may be resumed by restarting the copying process when the document in question has been fed to the light exposure station.
As a result, it is possible to eliminate trouble with document feeding, including the tendency for curling, because the document is outputted back to the document tray without lying in the feeding path.
Nevertheless, it will also be appreciated that with such a construction, a double-sided document must be returned to the document tray via a path which inverts the document, and too much time is required to restore the document to its original loaded state, and in some cases even after the trouble has been solved the document is not restored to its original loaded state. That is, in the case of either simplex or duplex copying of double-sided documents, the requirement for the front and back sides of the documents to be inverted makes it necessary for the documents to be fed repeatedly via an inverted feeding path.
Furthermore, with a large number of document pages, or double-sided documents, resumption of copying after clearing of trouble involves a much greater length of time for the document to reach the light exposure station because it must pass through an inverted feeding path. Since the feeding control requires the feeding via the inverted feeding path each time, much time is eventually spent.